This invention generally relates to battery packs for electric/hybrid vehicles and, more particularly, to a retention frame for a battery pack that reduces the relative motion between batteries within the pack.
It is well known in the art relating to battery packs for electric/hybrid vehicles to provide a structure for securing a plurality of batteries within the battery pack. Electric vehicles require a battery pack having both high voltage and large current capacity. To provide the necessary voltage and current capacity to drive the vehicle, the battery packs generally include a number of individual batteries electrically coupled together. Usually, the batteries are held in place by a compressive force applied to their top surfaces. Some battery pack designs arrange the batteries on an underlying support or tray and hold down the batteries on the support by means of a cover that applies the compressive force to the top surfaces of the batteries and is secured to the underlying support.
Over time, the force applied to the tops of the batteries tends to relax or decrease. As this force is reduced, the batteries become more susceptible to relative shifting which leads to less than optimal performance over time. There is a need for a battery pack configuration that reduces the relative motion between the batteries which results in increased life and reliability of the electrical connections between the batteries.
The present invention provides a battery pack for an electric/hybrid vehicle. The pack includes a plurality of batteries stacked in layers one atop the other. The plurality of batteries is supported on a base. Spacers are disposed above and below each layer of batteries. The spacers hold the batteries in place and also provide air passages around the batteries. The air passages allow air to flow around the batteries to provide heating or cooling of the batteries. A retention frame affixes the batteries to the base to prevent relative movement between the batteries. The frame includes a plurality of beams that are interconnected and extend along ends of the batteries. The beams apply a vertical force against the batteries, thereby holding them down in place. By restricting the movement, it is less likely that the electrical connections between the batteries are disrupted.
In one embodiment of the invention, each battery includes an end bracket mounted on each end of the battery. The beams are arranged such that they are located over the end brackets of the batteries when the batteries are arranged in rows. The beams are secured to the end brackets by aligning holes in the beams with holes in the end brackets and placing fastening elements such as bolts or screws through both holes.
The frame includes a layer of beams for each layer of batteries. The layers are secured to together by fastening elements such as bolts or screws that extend between each layer. A bottom layer of the beams is secured to the base. Thus, the configuration of the frame applies a vertical force against the end brackets of the batteries, thereby holding the batteries down in place.
The spacers provided above and below the layers of batteries are divided into sections that form the rows in which the batteries are placed. Each section includes end walls and side walls which may be shared with an adjacent section. A horizontally disposed edge portion extends outwardly from the walls within each section. The bottom edges of the batteries are seated against the edge portion when the spacer is located beneath the batteries and the edge portion rests upon the top edges of the batteries when the spacer is located above the batteries, thereby creating air passages above and beneath the batteries. Also, a sheet of material is placed between the spacers to create air passages.